This invention relates to glass fiber production and, more particularly, to an improved microcomputer controlled winder for attenuating a plurality of streams of molten glass into fibers and for collecting the fibers as a strand on a wound package.
One method for manufacturing textiles from glass involves attenuating a plurality of streams of molten glass into fibers, collecting the fibers into a strand and winding the strand into a package for subsequent use in manufacturing various products. The molten glass initially flows at a controlled rate from a furnace forehearth into a feeder or bushing which has a plurality of orifices formed in its bottom. As the molten glass flows from the orifices, it is pulled downwardly at a high rate of speed for attenuation into fibers. A plurality of attenuated fibers are then gathered together into a strand, coated with a sizing, and the strand is wound onto a package on a winder collet. The speed of the winder is controlled in an attempt to maintain a uniform attenuation speed, which in turn produces a uniform diameter in the attenuated fibers if other conditions such as the temperature of the molten glass remain constant. Since the strand is wound onto a core to form a package, the diameter of the package will gradually increase. As the diameter increases, the rotational speed of the collet must be simultaneously decreased to maintain a constant attenuation rate.
Various controls have been known in the prior art for controlling a winder collet speed for maintaining a substantially uniform attenuation rate as the size of a package on which glass fibers are wound changes. In a typical prior art system, a digital computer or other process controller stores data corresponding to a desired winder collet speed at different predetermined points of time after the start of winding a package. At each of these points of time, the winder collet speed is sampled and compared with the desired speed for generating an error signal. The error signal is used to modify the winder collet speed in order to reduce the deviation between the desired speed and the actual speed. In one prior art system, as illustrated in U.S. Pat. No. 3,471,278 which issued Oct. 7, 1969, the winder speed is controlled by means of a magnetic clutch connecting a constant speed motor to a generator. The output from the generator in turn drives the winder motor. A digital computer generates an output signal which is converted to an analog signal for driving a ramp function generator. The ramp function generator in turn drives the magnetic clutch to warp or ramp down the speed of the winder collet as the diameter of the package increases to maintain a constant fiber attenuation and strand collection speed. In order to change the product collected on the winder, a different analog winder speed ramp curve must be stored in the digital computer. Since the system requires analog signals for controlling the winder, some degree of error may enter into the winder speed, which in turn results in a variation of the diameter of the attenuated fibers.